title: Lack of protective efficacy in buffaloes vaccinated with Fasciola gigantica leucine aminopeptidase and peroxiredoxin recombinant proteins.
abstract: Gene coding for leucine aminopeptidase (LAP), a metalloprotease, was identified in the tropical liver fluke, Fasciola gigantica; that on sequence analysis showed a close homology (98.6%) with leucine aminopeptidase of the temperate liver fluke, Fasciola hepatica. The recombinant leucine aminopeptidase protein was expressed in Escherichia coli. F. gigantica peroxiredoxin, a hydrogen peroxide scavenger and an immunomodulating protein, was also cloned and expressed in E. coli. A vaccination trial in buffaloes was conducted with these two recombinant proteins, with 150 and 300 μg of leucine aminopeptidase and a cocktail of 150 μg each of recombinant leucine aminopeptidase and peroxiredoxin in three groups, respectively. Both Th1- and Th2-associated humoral immune responses were elicited to immunization with these antigens. A challenge study with 400 metacercariae did not show a significant protection in terms of reduction in the worm burden (8.4%) or anti-fecundity/embryonation effect in the immunized groups, as to the non-immunized control animals. Our observations in this buffalo vaccination trial are contrary to the earlier promise shown by leucine aminopeptidase of F. hepatica as a leading candidate vaccine molecule. Identification of leucine aminopeptidase gene and evaluation of the protein for its protective efficacy in buffaloes is the first scientific report on this protein in F. gigantica.
authors.affiliation: Division of Parasitology, Indian Veterinary Research Institute, Izatnagar, Bareilly, U.P. , India. rainaok@rediffmail.com
authors.forename: O K
authors.initials: OK
authors.lastname: Raina
authors.forename: Gaurav
authors.initials: G
authors.lastname: Nagar
authors.forename: Anju
authors.initials: A
authors.lastname: Varghese
authors.forename: G
authors.initials: G
authors.lastname: Prajitha
authors.forename: Asha
authors.initials: A
authors.lastname: Alex
authors.forename: B R
authors.initials: BR
authors.lastname: Maharana
authors.forename: P
authors.initials: P
authors.lastname: Joshi
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D000947:Antigens, Helminth / Q000235:genetics / Q000276:immunology*; D002020:Buffaloes; D003001:Cloning, Molecular; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005209:Fasciola / Q000235:genetics / Q000276:immunology*; D005211:Fascioliasis / Q000276:immunology / Q000517:prevention & control*; D015870:Gene Expression; D007931:Leucyl Aminopeptidase / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D054464:Peroxiredoxins / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D017422:Sequence Analysis, DNA; D014612:Vaccines / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D018509:DNA, Helminth; D011994:Recombinant Proteins; D014612:Vaccines; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic; D054464:Peroxiredoxins; D007931:Leucyl Aminopeptidase